1、On top of that, coprolites, as palaeontologists politely describe fossil faeces, have turned up with ammonite shells in them.
2、Some palaeontologists think them members of a phylum that is now extinct.
3、That is why the recent discovery of a Jurassic ammonite with a shark's tooth embedded in its shell has excited palaeontologists.
4、Because many palaeontologists base their work on the shape of fossils alone, their methods of conservation are not designed to preserve DNA.
5、Rather than counting individual species of fossils,which vary over time, palaeontologists who study extinction usually countentire groups of related species, called genera.
6、Until now, palaeontologists have thought the recovery took tens of millions of years—a reflection either of the profundity of the Great Dying or of the toxic desert planet that the eruptions created.
